I have problems solving an electric circuit. I need to find the red drawn "I" (Current). However the way the electric circuit is drawn strikes me. I have very basic knowledge of physics and my skills are limited. The way I tried to attempt the problem is to look at the bottom left triangle and the top right triangle. I then used the Mesh-Current-Method for the bottom left triangle which I defined as: $m_1 = -U_q_1 + U_1 + U_3 + U_q_3$ ($U_1$ is the Voltage at $R_1$ and $U_3$ the Voltage at $R_3$). This term must be equal 0 due to Kirchoff law. Knowing $U_q_1$ and $U_q_3$ (both 5V) we are left with $m_1 = U_1 + U_3$. As far as I know $U_1$ and $U_3$ cannot be negative, so I assumed that both are 0V (due to the addition). Repeating this for the upper triangle returns me $U_2 = 0$. With Ohm's law $I$ must be 0. However my own intuition is that I did something wrong. Any ideas?